Protective apparatus



Filed Feb. 28, 1928 Muzak His Attovneu.

Patented May .28, 1929.

UNI-TED STATES JOSEF BIERMANNS, OF KARLSHORST, GERMANY,

ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

PROTECTIVE APPARATUS.

Application filed February 28, 1928, Serial No. 257,731, and in GermanyApril 4, 1927.

My invention relates to improvements in protective apparatus, and moreparticularlyto improvements in protective relays for electric circuitsand especially relays of the type whose time of operation is dependenton the distance between the relay and the fault point. An object of myinvention is to provide improved protective apparatus whereby on theoccurrence of abnormal circuit conditions so to change the mode ofoperation as to obtain an improved time characteristic. I

My invention will be better understood from the following descriptionwhen considered in connection with the accompanying drawing and itsscope will be pointed out in the appended claims.

Fig. 1 illustrates partly in diagram and partly in perspective anembodiment of my invention, and. Fig. 2 illustrates diagrammatically amodification of. a part of my invention.

Relays whose time of operation or release is dependent on the circu tcurrent and voltage to get operation in such a manner that with areduction in voltage operation may takeplace in a shorter time and/or ata lower current, are known. Apparatus embodying my invention, however,operates,in.acc0rd ance with the followin principles. If a force or atorque depen ent on the current ofva circuit is exerted on a movablemember such as a Ferraris disk and is opposed by a torque dependent onthe voltage so as to be at rest normally, then the current necessary tomove the disk against the voltage torque is dependent on the ratio ofthe current to the voltage. If the disk, when actuated by the currenttorque, is damped by eddy currents produced in it and depepdent on thevoltage, then the speed of the disk is also dependent on this condition.On the movement of the disk the direct torque exerted by the voltageshould be negligibl damping torque and the direct torque may be madeentirely ineli'ective at the moment mob tion begins.

If the forces exerted by the current and voltage vary proportionallytherewith, then proportionality is also obtained between a current towhich the device res onds and the time of operation on the one and andthe distance on the other, that is to say, the time is directlyproportional to the current'and inversely proportional to the voltage.This, however, is not always desirable and the chare in comparison withthe acteristic can be in accordance with other functions than the firstpower, for example, the second power.

Relays in which a Ferraris disk is con trolled by a current magnet and avoltage magnet are known. Since, however,.in these the effect of thevoltage magnet is based on the constant production of the opposingdirect torque, the time ofoperation is dependent on the difi'erencebetween the torques produced by the current and the voltage. Acharacteristic dependent on the ratio of the current and the voltage is,however, not obtained with such an arrangement.

In the embodiment of my invention shown in Fig.1 an electric circuithaving conductors 3, 4 and 5 is arranged to be controlled by a circuitbreaker 6 herein shown as of the latch closed type and-provided with atrip coil 7 The circuit of the trip coil is arranged to be controlled inaccordance with my invention by protective apparatus such as a relay 8Whose mode of operation is subject to change on the occurrence of.abnoral circuit conditions.

The relay 8 as shown-comprises a movable element, such as a rotatableelectric current conducting member or F erraris disk 9, the movement ofwhich is arranged to be controlled by' a plurality of electromagneticmeans such as motor elements 10 and 11 which as shown are inductivelyrelated to the member. The motor element 10 is respon ive to a currentof the circuit 3, 4, 5 and includes, as shown, a magnetic core 12provided with windings 13, 14 and 15 and a cooperating magnetic member16. The windings 13, 14

and 15 are connected to be energized in accordance with the current in aconductor 5 of the circuit by any suitable means such as the currenttransformer 17, suitable phase displacing means such as the resistor 18being connected in "circuit with the windings such as 13,14,15. Thismotor element 10 may e constructed as set forth in German Patent 316 599so as to provide a torque which is substantially proportional to thefirst power of the current. As pointed out in this patent, this may bedone by having the magnetic circuit of one of the windings such as 14arranged to become saturated at some predetermined current, for example,normal line cur rent. The motor element 10 exerts a torque which tendsto turn the disk 9 in the direction indicated by the arrow 19.

The motor element 11 as shown may be similar in construction to motorelement 10, that is comprising a magnetic member 12' whose branches areprovided with windings tial transformer 20. Suitable phase displac-.

ing means such as a resistance 18 may be placed in circuit with thewindings 13", 14',

15. The .motor element 11 normally exerts a direct torque which opposesthe torque of the current element 10 and tends to turn the disk in thedirection indicated by the arrow 21. Motion in this direction is limitedby,

suitable means such as an extension 22 on the shaft 23 which supportsthe disk, this extension coming to rest against a stop 24.

In accordance with my invention, the movement of the disk is arranged tocontrol the circuit of one of the windings 13'15' of the voltage element11 so as to change the action thereof from a direct torque toa dampingtorque, when the current element 10 'in response to current of apredetermined value exerts a torque which is sufficient to overcome orpredominate the direct torque of the volt-v ,age element. For thispurpose I may provide in the circuit of the winding 13'-15' contacts 25which are arranged to be actuated by the extension 22 so that they arenormally closed and are arranged to be opened on the movement'of thedisk. The extension 22 may also be arranged to control contacts 26 inthe circuit of the trip coil 7 after a predetermined movement of thedisk in the direction indicated by the arrow 19.

Under normal circuit conditions, the direct torque of the voltageelement 11 predominates over the opposing direct torque of the currentelement 10 'to'hold the extension .22

. in the position shown in Fig. 1 whereby to maintain the circuit of thewinding 13' -15' closed.. ()n the occurrence of a fault, involving, forexample, the conductor 5 of the circuit 3, 1, 5 and causing the currentto rise and usually the voltage to fall, the direct torque of thecurrent element 10 predominates to overcome the direct torque of thevoltage element 11 and thereby efiects movement of the disk in thedirection indicated by the arrow 19. On the initial movement of thedisk, the extension 22 releases one of the contacts 25 and thereby opencircuits the windin 13' 15' circuit opening movement it being limited bya stop 25'. In this way the motor element 11 ischangedfrom a directtorque device to a damping torque device whose torque can be madeproportional to the voltage by any suitable means. Consequently the disk9 is turned at a speed which 1s directly proportional to the torqueexerted by the current, that is, proportional to the current ,andinversely proportional to the damping force or torque exerted by thevoltage that is inversely proportional to the voltage. If the disk 9moves sufficiently for the *extension 22 to ,engage the contacts 26,then the energization of the trip coil 7 and the release of the circuitbreaker 6 is effected. In order to restore the disk 9 from the trippingto the normal or rest position a small counterforce or torque means suchas a spring 27 may be provided.

The contacts 25 may be used to change the operation oi? the voltageelement from a direct torque device to a damping torque device in amanner diiierent from that shown in Fig.

- 1. For example, as shown in Fig. 2, the circuit of suitable phasedisplacing devices such as'an impedance 28 may be controlled in anysuitable manner to eliect a change from a direct torque to a dampingtorque so as to obtain the desired characteristic. Thus in Fig. 2 itwill be noted that when the contacts 25 are opened all three of'thewindings 13', 14, 15' are eiiective to produce damping flux as comparedwith only one winding in Fig. 1.

While I have shown and described my invention in considerable detail, Ido not desire to be limited to the exact arrangements shown, claims allthose modifications that fall withbut seekto cover in the appended inthe true spirit and scope of my invention.

What I claim as new and desire to secure by LettersPatent of the UnitedStates is 1., In a protective relay for an electric circuit, a movableelectric current conducting member, electroresponsive means for moving.the member in one direction, electromagnetic means inductivelyassociated with the member and arranged normally to exert thereon a'direct opposing action tending to prevent movement of the member insaid direction by said electroresponsive means, and means arranged to beoperated on movement of the member in said direction to change theaction of said electromagnetic means from a direct opposing action to anaction dependent on the speed of the member.

2. In a protective relay for an electric circuit, a rotatable electriccurrent conducting member, electroresponsive means for turning themember in one direction, electromagnetic means inductively associatedwith the member and arranged normally to exert thereon a direct torquetending to prevent movement of the member in said direction by saidelectroresponsive means, and means arranged to be operated on rotationof the member in said direction to change the action of saidelectromagnetic means from a direct torque. to a damping torque.

3. A relay including a rotatable electric current conducting member andmeans for controlling the movement thereof, including a plurality ofelectromagnetic means arranged to exert opposin torques on the member,one of said means eing inductively related to the member, and meansoperative in response 'to the movement of the member when the torque ofthe other means is predominant for changing the action of said one ofsaid means from a direct torque to a damping torque.

4. A relay including a rotatable electric current conducting member andmeans for controlling the movement thereof, including a plurality ofelectromagnetic motor elements inductively associated with the memberand arranged to exert thereonbpposing direct torques, and meansoperative in response to the movement of said member when the torque ofone of said elements predominates over the torque of the other forchangingthe action of the other element from a direct torque to adamping torque.

-5. A relay including a. rotatable electric current conducting memberand means for controlling the movement thereof including a plurality ofelectromagnetic motor elements inductively associated with the memberand arranged to exert thereon opposing direct torques, and meansoperative in response to the movement of the member when the torque ofone of said elements predominates over the torque of the other tocontrol the circuit of a winding of said other element whereby to causesaid other element to operate as a damping magnet.

6. In combination with an electric circuit, circuit controlling meansincluding a protective relay having a rotatable electric currentconducting member, and means for controlling the movement thereofincluding a plurality of electromagnetic means inductively associatedwith the member, one being arranged to be energized in accordance withthe current of the circuit and to tend to move the member in onedirection and another being arranged to be energized in accordance withthe voltage of the circuit normally to exert a direct torque on themember whereby to prevent movement thereof until overcome by saidcurrent energized means on the occurrencc of an over-current condition,and

means responsive to the movement of the member for ehangin the action ofsaid electromagnetic means t i'om a direct torque to a damping torque. v

In a protective relay for an electric cira rotatable electric currentconducting and means for controlling the movement cuit, disk thereofincluding a plurality of electromagto be operated on movement of themember in said direct1on; to change the action of said other elementfrom a direct torque to a dampmg torque.

8. In combination, an electric circuit and circuit controlling'meansincluding a protective relay having a rotatable electric currentconducting member and electroresponsiv'e means for controlling themovement thereof, including a plurality of electromagnetic meansarranged to exert on the member opposing torques respectively dependenton the current and the voltage of the circuit, said voltage responsivemeans being inductively related to the member, and means operative inresponse to the'movement of the member when the torque of the currentresponsive means predommates for changing the action of the voltageresponsive means from a direct torque to a damping torque.

In witness whereof, I have hereunto set my hand this 10 day of February,1928.

JOSEF B'IERMANNS.

